Tales of Science and Adventure

Month: September 2014

Disclaimer: Trading Atoms has no interests, financial or otherwise, in any biotechnology or related company.

The development of Genetically Modified Organisms (GMOs) is clearly one of the more controversial issues of our time, with a wellspring of strongly held opinions issuing forth, particularly from the political left. With such widespread distrust and uncertainty amongst concerned citizens, the topic is well and truly ripe for some informed discussion. Riper than a GM Flavr Savr tomato, some might even suggest.

In this first instalment on GMOs, we’ll be going through the basics of just what genetic modification means. Stay tuned for Part 2 where we’ll walk you through a simple guide on how to make your very own GMO, then in Part 3 we’ll address the more sobering question of whether the technology is even safe, and possibly have you regretting that spider-shark you’ve unleashed upon the world.

A Quick Review of Genetics

As you would surely have heard at some time, all living creatures have DNA (deoxyribonucleic acid) in them. If you’d like to get a bit spiritual-sciencey (as we sometimes do), you can legitimately think of DNA as the mystical life force that vibrates through and connects all living creatures on the planet. It is the real-world midichlorians. This particular molecule is present in every single life form, from the elegantly simple bacteria, to the towering trees, to the most majestic of animals.

Pretty much everything you need to remember about DNA is contained in the following three sentences. DNA is an incredibly long spiral ladder, with four types of rung. These rungs are organised into genes. Each gene is a blueprint to make a certain protein.

When the word ‘protein’ gets mentioned, most people think of that new diet they’re trying, or how sigh, they really should be making better use of that gym membership. While it’s true that muscles are largely made up of two particular types of proteins, there are many, many more types. It’s actually best to think of proteins as tiny machines that swim around in your cells, controlling every single thing you ever do. They are like the little cogs whirring away driving the immense living robot that is your body.

So to recap:

DNA –> is organised into –> Genes –> are blueprints for –> Proteins –> are tiny machines that control everything you do

A protein-machine grabbing onto pink DNA

How Many Genes are There?

Humans are intricately complex beings, with a huge array of different cell types and processes going on. Before the Human Genome Project, scientists speculated about how many different types of genes and proteins we must have to sustain all this complexity. Guesses ranged from over 6 million genes back in the ’60s, down to 100,000 genes by the National Institute of Health in 1990, to a post-genome estimate of 22,000. Recent evidence suggests the number is probably actually around 19,000 to 20,000.

Whatever the exact figure, it’s still very large, especially considering that those sweet guns you’ve been working on are mostly made up of just two proteins. Out of the thousands of others, only a small handful are well understood, and many remain outright mysterious.

How many Genes are there in Other Branches of Life?

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Bearing in mind that it’s very hard to say exactly how many genes any species has, geneticists have found some interesting results:

So if you thought that humans were a superior species genetically, think again. While we do have very impressive brains, our gene sets are not so different from a whole bunch of everyday animals. If you’ve ever been unlucky enough to suffer a bout of vaginitis, you may have Trichomonas vaginalis to thank – a single-celled parasite with three times as many genes as you.

Plants in particular can have staggeringly large gene sets. This is often the result of accidental DNA duplications that occur during evolution, which are then chosen by selective breeding (more on that below).

This discussion of gene sets is actually quite facetious, because what has become clear over time is that the number of genes doesn’t really matter. Merely witness the devastation that HIV is able to wreak with its measly nine genes. The important thing to remember is that most species have thousands of genes, and we generally have very little idea what they do.

Your body doesn’t know what any of the original 95,000 proteins are, and we’re not specially adapted to be able to deal with them. Rather, imagine a conveyor belt manned by thousands of eager unsupervised 5-year olds, with intricate Lego creations travelling along it. It’s going to be an orgy of joyful destruction.

Our digestive systems are much like this. Whatever shape or function a protein has, this becomes irrelevant once it enters the stomach. Gastric juices and enzymes will tear apart everything. The two extra wheat proteins will be broken down just like all the others.

It is possible that, while still in the wheat, the drought resistance proteins could make a chemical that is relevant to human health, such as bacteria that produce insulin. For this reason not all GMOs are equal, and the functions of introduced proteins have to be well understood. In most cases though, the only difference between GMOs and “wild” strains will be one or two extra proteins. We’ll explore health risks of GMOs further in Part 3.

What isn’t Genetic Modification?

An organism can be considered GM if even a single rung in its DNA ladder is changed – even if that rung does absolutely nothing. Let’s return to our legal definition:

“Any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology.”

The important clause is “through the use of modern biotechnology.” What this means is that the DNA has to be altered in a specific fashion for it to count as genetic modification. Otherwise – bizarrely – any changes are considered natural.

There are several ways that DNA can be altered without the use of modern biotechnology. As we shall see, these “non-GM” methods generally result in far more significant and unpredictable changes.

carrotmuseum.co.uk

The oldest way that humans have been modifying DNA is through the 10,000 year-old practice of selective breeding. An example of this is cultivating crops with duplicated sets of genes. These plants typically have larger fruit and tens of thousands of newly evolving genes. Humans have also both accidentally and intentionally created hybrid species, throwing together thousands of unfamiliar genes from two species. Modern staple crops, like maize, wheat, rice and fruit trees, are all human-created mutants which differ wildly from their natural ancestors.

A far more rapid process is that of random mutagenesis. If adding one gene using biotechnology was like carefully painting a single dot on a piece of canvas, random mutagenesis is Jackson Pollock. It involves splattering random and sometimes catastrophic changes all throughout a species’ DNA, potentially affecting hundreds of genes at once. This can be achieved chemically with a substance like EMS, but another method frequently used by farmers, “radiation breeding”, simply involves shining a little X-ray or gamma radiation on seeds before planting them. China has even sent seeds to space to give them a nice gamma ray bath.

Predictably enough, random mutagenesis is massively destructive to most of the seeds exposed. However, sometimes a few will mutate in just the right way to gain new functionality such as faster growth or better yield, and these are what farmers are after.

Unlike GM strains created with modern biotechnology – which have to be extensively characterised and regulated – randomly mutagenised seeds are rarely (if ever) characterised, let alone disclosed to consumers as being mutants. Almost no country except Canada has any regulatory restrictions or requirements around the practice, nor does random mutagenesis violate any country’s organic standards.

Thinking about this for a second, we reach an absurd yet true conclusion. It’s completely possible that:

a) A specific mutation could be created in a lab using modern biotechnology. Meanwhile at a farm, completely by chance, the same mutation could be created using random mutagenesis. The resulting two organisms would be identical, but only one of them would ever be characterised, labelled or regulated.
b) An organic company that was fervently against “GMOs” could employ random mutagenesis in their crops. In fact, have you ever bought an organic Rio red grapefruit?

The practice of radiation breeding is on the rise, and possibly far more prevalent than anyone realises. Furthermore, there are solid arguments that conventional GMOs pose less threat than randomly mutagenised seeds. As a result, the current regulatory situation is, to put it politely, extremely strange.

The development of GMOs is an important issue for us to collectively address as we move into the future. Until the science is understood by people like you and me, no informed policy decisions can be made, and we’ll be stuck with the kinds of illogical regulations that currently exist. So if you’ve made it this far, congratulations! You’re a part of the solution, and next time you hear the term “GMO” you can think, “Aha. That means a protein has probably been added.”